Once considered subspecies, there are now two recognized species of pigtail
macaques. Macaca nemestrina, or the southern pigtail macaque, is the
only species studied in the wild, and little is understood about the ecological
or behavioral differences of the two species. In captivity, studies have been
conducted with both species, though often without knowing which species is
which (Groves 2001; Maestripiri pers. comm.). The information provided in this
fact sheet is about the southern species, except where noted.

MORPHOLOGY

Southern pigtail macaques have olive brown fur over their entire bodies, except
for their undersides, which are white. The fur on the top of their heads is
dark brown or black and grows in a pattern that makes them look like there
is a depression in the center of the top their heads (Rowe 1996; Groves 2001).
Northern pigtail macaques have golden brown fur and the fur on the top of their
heads is brown. They have red streaks of fur extending from the outer cornier
of each eye towards the ear. Pigtail macaque infants are born black and as they mature, their
pelage changes
to the adult coloration (Crockett & Wilson 1980).
Pigtail macaques are sexually
dimorphic with males measuring 495
to 564 mm (1.62 to 1.85 ft) and weighing 6.2 to 14.5 kg (13.7 to 32.0 lb) while
females measure 467 to 564 mm (1.53 to 1.85 ft) and weigh between 4.7 and 10.9
kg (10.4 and 24.0 lb) (Fa 1989). Males have much larger canine teeth than females,
measuring 12 mm (.472 in), on average, which are used in aggressive interactions
(Rowe 1996). Pigtail macaques have an abbreviated tail, less than the length
of the body from head to rump, which is often bare or covered only by sparse
fur (Rowe 1996; Groves 2001). Pigtail macaques get their popular name from their
tails, which are short and carried half-erect so that they somewhat resemble
a pig's tail (Choudhury 2003). They move
quadrupedally on
the ground and through trees (Rowe 1996). Pigtail macaques have an average lifespan
of about 26 years (Sponsel et al. 2002).

RANGE

Pigtail macaques have a wide range throughout Southeast Asia. Southern pigtail macaques
are found in northeastern India, southern China, in Indonesia on Borneo (Kalimantan) and Sumatra, in eastern
Bangladesh, as well as in Burma, Thailand, Laos, Cambodia, and Vietnam. They
are also found in Malaysia, both on the Malay Peninsula and on Borneo (Feeroz
et al. 1994; Groves 2001; Choudhury 2003). Northern pigtail macaques are found in peninsular Thailand , through Burma and
Indochina and into Bangladesh , India , and Southern China . There is some evidence
of hybridization of the two species in Thailand, but interbreeding is not widespread
(Groves 2001).

HABITAT

Pigtail macaques are found in lowland and hilly
primary rainforests and occasionally are found
in swamp and secondary forests (Crockett & Wilson 1980).
They prefer undisturbed forests and are found in the highest densities in intact rainforests
(Supriatna et al. 1996). Rainforests are maintained in warm and humid climates where temperatures range between 18 and 30° C
(64 and 86° F) and where there is more than 2500 mm (8.20 ft) of rainfall each year, though
there may be seasonality in rainfall. Where they are found in Bangladesh, the annual precipitation
is 2034 mm (6.67 ft) with the highest rainfall occurring during the monsoon season, from May to
September, and the lowest in December. The coldest months of the year are December and January,
which have average temperatures of 12.3° C (54.4° F) and 9.7° C (49.5° F), respectively. August is
the warmest month of the year with an average maximum temperature of 33° C (91.4° F) (Feeroz et al. 1994).
In neighboring northeastern India, the climate and rainfall is quite variable, ranging from less than
1000 mm (3.28 ft) to more than 10,000 mm (32.81 ft) annually (Choudhury 2003). The climate in this part of India can also
be as cool as 4°C (39.2° F) in December to early February to 30° C (86° F) from June to August. Most
of the rain occurs from May to September, and snow falls in winter at the higher altitudes (Choudhury 2003).
Rainfall in southern Sumatra ranges from 2000 to 3267 mm (6.56 to 10.7 ft) per year with indistinct wet
or dry seasons (Supriatna et al. 1996). The climate there is also warm and humid (Lucas & Corlett 1991).
In Peninsular Malaysia, rainfall averages 2100 mm (6.89 ft) per year with the least amount of rainfall
during January and February and the period of highest rainfall occurring during September and October
(Saiful & Nordin 2001).

ECOLOGY

Pigtail macaques are highly frugivorous,
with 74% of their diet consisting of fruit, but they also consume a wide variety
of foods including insects, seeds, young leaves, leaf stems, dirt, and fungus
(Crockett & Wilson 1980; Caldecott 1986). Pigtail macaques spend most of their time on the ground, but the northern pigtail
macaque seems to be more arboreal than the southern species (Maestripieri pers.
comm.). Spending most of their time on the ground foraging,
they are particularly adept at raiding agricultural fields and obtaining coconuts
from oil palm plantations, papaya, corn, and cassava. They are stealthy crop
raiders, sneaking silently into a garden one at a time, with one acting as a lookout and
calling an alarm vocalization if humans are seen. Pigtail macaques are especially
likely to raid crops during rainstorms, when farmers are inside, away from their
crops (Crockett & Wilson 1980). In some areas of the Malay
Peninsula, farmers keep and train pigtail macaques to retrieve coconuts and fruits
from cultivated trees (Crockett & Wilson 1980; Sponsel et al. 2002).

Because of their large group size, between nine and 81 individuals and larger,
pigtail macaques often split up into foraging groups to decrease direct competition
for fruit at feeding sites. They travel in small subgroups, from two to six monkeys,
along the ground, foraging as they move and keeping in contact with other subgroups
through vocalizations (Crockett & Wilson 1980; Caldecott 1986). In addition
to spreading out over the landscape as they forage, pigtail macaques cover large
areas each day. They have home ranges between .6 and 8.28 km² (.232
and 3.20 mi²) and in areas of high density, groups' home ranges can
overlap each other by as much as 50% (Sponsel et al. 2002). The day range length
varies between 825 and 2964 m (.513 and 1.84 mi), depending on weather conditions
and seasonal fruit availability (Caldecott 1986).

Disclaimer: The Wisconsin Primate Research Center provides Primate
Info Net as an informational service.We are not responsible for the content of
linked sites, nor does inclusion of a link imply endorsement of the
views expressed in that content.